Journal of Bioactive and Compatible Polymers

Poly(D,L-lactide)'s (PLA) with different molecular weights were added to 2-cyanoacrylates (CA) to modify the physical properties of CA as a sur gical adhesive. The CA's used were ethyl 2-cyanoacrylate, isobutyl 2-cyano acrylate, and ethoxyethyl 2-cyanoacrylate. The viscosity and the set time of CA increased, and the bond strength reached a maximum, when the concentration of PLA with the molecular weight of 420,000 increased for the three CA's. To evaluate the toxicity of the mixtures, microspheres were prepared from the polymer of CA and PLA, and added to the medium for the culture of 3T3 cells. It was found that the PLA addition to ethoxyethyl 2-cyanoacrylate resulted in a decrease of the cell growth inhibition by the ethoxyethyl 2-cyanoacrylate polymer. Isobutyl 2-cyanoacrylate exhibited no significant inhibition on the 3T3 cell growth.

Surface pressure and surface potential studies of poly(isobutyl- cyanoacrylate) monolayers spread at the air-water interface were performed in the presence and in the absence of ampicillin in the aqueous subphase. They reveal that penetration/adsorption of the drug is enhanced when isobutyl- cyanoacrylate was polymerized in presence of adjuvants (glucose and dextran). Surface pressure-area experiments clearly show that the association which forms ampicillin with the adjuvant free polymer is weak and can easily be dis rupted. This association is strong enough to resist high compression in the case of the adjuvant loaded polymer.

Polyvinyladenine [poly(VAd)] and poly(vinyladenine-alt,co-maleic anhydride) [poly(VAd-MA)] were prepared by free radical polymerization of vinyladenine and copolymerization of vinyladenine with maleic anhydride.

As a model of a primitive enzyme block-copoly(amino acid)s con taining L-serine and L-aspartic acid as the repeat unit were prepared. Spectro scopic measurements indicate that some block-copoly(amino acid)s, especially ABAB and ABABA types, do form folded conformations. Hydrolysis reactions of p-nitrophenyl p-guanidinobenzoate were accelerated in the presence of ABAB and ABABA type block-copoly(amino acid)s compared with a random copoly (amino acid). From these results we speculate that primitive enzymes were born by assembling block-copoly(amino acid)s.